Bacteriorhodopsin, the simplest known ion pump, is related tot he rhodopsin family of seven-transmembrane-helix receptors. Our research is designed to characterize specific intermediate steps in the proton pump mechanism and to explore the newly emerging structural analogies between bacteriorhodopsin and certain neurotransmitter and hormone receptors. 1. Proton pump mechanism; a. From which amino acid is the transported proton released into the extracellular medium: b. What parts of bacteriorhodopsin undergo conformational changes during the steps that reset the pump? 2. Relationship to seven-transmembrane-helix receptors; How does retinal gain access to its binding pocket in bacterio-opsin to form bacteriorhodopsin? Minority students will activity participate int he research. One undergraduate will study protein conformational changes by FTIR spectroscopy and a second undergraduate will measure the rate of retinal binding to bacterio-opsin. A graduate student will investigate chemical modification reactions of bateriorhodopsin mutants. All students are expected to present their results at regional or national meetings.